Chemical liquid supplying apparatus and pump assembly

Abstract

A chemical liquid supplying apparatus, which can discharge chemical liquid with high precision, is provided. A pump assembly is detachably mounted in a pump case in which liquid inflow and discharge ports are formed. The pump assembly includes: a cylindrical body in which a piston is slidably incorporated axially; an elastically deformable bellows forming a pump chamber in the pump case and forming a drive chamber in which an indirect medium is enclosed; and an axially elastically-deformable bellows cover continuing with a sliding surface of the piston and forming a seal chamber in which the indirect medium is enclosed, and the pump assembly is unitized. The pump assembly is coupled to a drive shaft via a connecting member, and by axial-directional reciprocating movement of this drive shaft, the piston causes the bellows to perform a pump operation, whereby the chemical liquid is discharged from a liquid discharge portion.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]Applicant hereby claims foreign priority benefits under U.S.C. §119 from Japanese Patent Application No. 2007-312164 filed on Dec. 3, 2007, the contents of which are incorporated by reference herein.TECHNICAL FIELD OF THE INVENTION[0002]The present invention relates to a chemical liquid supplying apparatus and a pump assembly, which discharge a fixed amount of chemical liquid such as photoresist liquid.BACKGROUND OF THE INVENTION[0003]On surfaces of semiconductor wafers, glass substrates for liquid crystal display device, or the like, minute circuitry patters are formed by a photolithography step and an etching step. In the photolithography step, a chemical liquid supplying apparatus is used to apply chemical liquid such as photoresist liquid onto the surfaces of the wafers or glass substrates, and the chemical liquid accommodated in a container is sucked up by a pump and passes a filter and the like to be applied onto applied materials s...

AI Technical Summary

Benefits of technology

The present invention provides a chemical liquid supplying apparatus and pump assembly that can discharge chemical liquid with high precision. It also prevents leakage of the incompressible medium and improves the lubrication characteristic of the seal member. The technical effects of the invention include high-precision chemical liquid discharge, prevention of incompressible medium leakage, and improved seal member lubrication.

Problems solved by technology

In addition, similarly to the above even when the incompressible medium leaks out, the movement strokes of the bellows and the like do not correspond to the discharge amount of the chemical liquid, whereby it becomes impossible to discharge the chemical liquid with high precision.

However, at the same time, the incompressible medium exposed to the outside disappears from a surface of the piston due to partially gradual evaporation or drying of the incompressible medium, whereby an amount of the incompressible medium decreases.

In addition, when the incompressible medium exposed to the outside volatilizes, since the incompressible medium functioning as lubricant disappears from the outer circumferential surface of the piston and becomes in a state where an oil film runs out, the seal member contacts directly with the outer circumferential surface of the piston, which results in progress of abrasion of the seal member.

However, there is such a tendency that pressure applied to the incompressible medium in the bellows type is lower than that in the syringe type.

For example, when resist is discharged to a nozzle via a filter, it is necessary to increase the pressure of the pump chamber because flow resistance of the filter is large.

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